Heretofore, organopolysiloxanes, especially dimethylpolysiloxanes have been utilized in fluid or cured form in a wide variety of industrial settings including electric, electronic, automobile, machinery, and building industries. However, as a result of the characteristics (low melting point, low glass transition temperature, and low van der Waals forces) of the base polymer or dimethylpolysiloxane thereof, these cured products are rubbery elastomers which only find a limited range of application because of their low modulus of elasticity and mechanical strength.
It was reported that organopolysiloxanes capable of forming cured products having a high melting point and a high modulus of elasticity can be obtained by introducing a divalent aromatic hydrocarbon group such as a phenylene group into the backbone of organopolysiloxanes. Based on this teaching, the following organopolysiloxanes were proposed.
(1) Polysilphenylenesiloxane ##STR2## See R. L. Merker, M. J. Scott, and G. G. Habeland; Journal of Polymer Science, Part A, Vol. 2, page 31 (1964).
(2) Poly(m-silxylenesiloxane) ##STR3## See H. Rosenberg and E. W. Choe; Organometallic Polymer "Symposium on Organometallic Polymers," New Orleans, 1977, Academic Press, page 239 (1978).
However, synthesis of these polymers (1) and (2) is cumbersome because of a need for Grignard reagents or metallic sodium.
There is a need for the development of a divalent aromatic hydrocarbon group-bearing organopolysiloxane which is easy to synthesize, has improved properties (such as a high melting point), which cures into a quality article, and thus can be useful in a wide variety of industrial applications.